Khanal Anil, Yusa Shin-ichi, Nakashima Kenichi
Department of Chemistry, Faculty of Science and Engineering, Saga University, 1 Honjo-machi, Saga 840-8502, Japan.
Langmuir. 2007 Oct 9;23(21):10511-7. doi: 10.1021/la7015098. Epub 2007 Sep 11.
A triple hydrophilic block copolymer composed of poly(ethylene oxide), poly(sodium 2-acrylamido-2-methylpropanesulfonate), and poly(methacrylic acid) (PEO-PAMPS-PMAA) does not form a micelle by itself when it is dissolved in water. However, if the anionic PAMPS and/or PMAA blocks are electrically neutralized with a cationic surfactant, such as cetyltrimethylammonium chloride (CTAC), micelle-like nanoaggregates are obtained, where the core is formed by the insolubilized PAMPS and/or PMAA blocks. Formation of the nanoaggregates was confirmed by dynamic light scattering (DLS) measurements and scanning electron microscopy (SEM), while the binding of CTAC to PEO-PAMPS-PMAA was monitored by electrophoresis measurements. The aggregates were characterized by fluorescence spectroscopy as well as DLS and SEM. It was found that the nanoaggregates have a spherical structure, and the hydrodynamic diameter ranges from 125 to 193 nm depending on the concentrations of the PEO-PAMPS-PMAA and CTAC. The critical aggregate concentration is on the order of 10-4 g L-1 when the ionic blocks of PEO-PAMPS-PMAA are fully neutralized with CTAC.
由聚环氧乙烷、聚（2-丙烯酰胺基-2-甲基丙烷磺酸钠）和聚甲基丙烯酸组成的三亲水性嵌段共聚物（PEO-PAMPS-PMAA）溶解于水时自身不会形成胶束。然而，如果用阳离子表面活性剂（如十六烷基三甲基氯化铵，CTAC）将阴离子型的PAMPS和/或PMAA嵌段电中和，就会得到类似胶束的纳米聚集体，其核心由不溶性的PAMPS和/或PMAA嵌段形成。通过动态光散射（DLS）测量和扫描电子显微镜（SEM）证实了纳米聚集体的形成，同时通过电泳测量监测CTAC与PEO-PAMPS-PMAA的结合。通过荧光光谱以及DLS和SEM对聚集体进行了表征。发现纳米聚集体具有球形结构，其流体动力学直径根据PEO-PAMPS-PMAA和CTAC的浓度在125至193nm范围内变化。当PEO-PAMPS-PMAA的离子嵌段被CTAC完全中和时，临界聚集体浓度约为10-4gL-1。
